JP5509789B2 - Optical member and EL display device - Google Patents

Description

  The present invention relates to an optical member for improving luminance in a self-luminous planar light emitting element such as an EL (Electro Luminescence) element or an FED (Field Emission Display), and an EL display using the same. Relates to the device.

  An EL element that is a typical planar light emitting element is an element that emits light depending on whether an electric field is applied to a fluorescent compound or an electric current is injected, and is divided into an inorganic EL and an organic EL depending on the material used.

  Luminescence due to electrical energy stimulation in fluorescent compounds is observed in inorganic compounds and organic compounds, but the excitation mechanisms of the respective emission centers are different. Inorganic EL elements emit light when electrons are accelerated in a phosphor under a high electric field and collide with the emission center to excite them. On the other hand, organic EL emits electrons and holes from outside. This is caused by exciting the emission center by their recombination energy. Both inorganic EL and organic EL have a sandwich structure in which a light emitting layer is sandwiched between electrodes, and a planar light emitting element can be obtained by making at least one of the electrodes transparent.

FIG. 9 shows a schematic diagram for explaining a very simple configuration of the organic EL element 100. The organic EL element 100 shown in FIG. 9 is configured by laminating a back electrode 101, an organic light emitting layer 102, a transparent electrode 103, and a glass substrate 104 in this order. Reference numeral 105 in the figure indicates an air layer. In such an organic EL element 100, light is emitted in the organic light emitting layer 102 by applying a voltage between the back electrode 101 and the transparent electrode 103, and this light is transmitted from the transparent electrode 103 side to the outside of the element, that is, air. It can be taken out to the layer 105 side.
In FIG. 9, only the back electrode 101, the organic light emitting layer 102, the transparent electrode 103, and the glass substrate 104 are shown. However, in an actual device, there are a number of various thin film layers such as an electron transport layer and a hole transport layer. It is configured by stacking. In addition, since a flexible EL element can be manufactured by using the glass substrate 104 as a plastic substrate, the glass substrate 104 is simply referred to as a substrate 104 below.

  By the way, the light emitted from the organic light emitting layer 102 is emitted to the air layer 105 through the transparent electrode 103 and the substrate 104. Generally, the refractive index of the material used for the organic light emitting layer 102, the transparent electrode 103, and the substrate 104 is Therefore, the organic EL element has a light extraction loss due to Fresnel reflection. The Fresnel reflectivity (R), which is an index of the Fresnel reflection that occurs at the interface where materials having different refractive indexes are in contact, is expressed by n1 as the refractive index of the first material in contact with each other and n2 as the refractive index of the second material. In this case, it can be expressed using these refractive indexes n1 and n2. For example, in the case of normal incidence, it is expressed by the following equation (1). The higher the value of such Fresnel reflectance (R), the greater the light extraction loss.

  Further, when the refractive index of the emission side material (refractive index: ns) positioned on the air layer 105 side is lower than the incident side material (refractive index: ni) positioned on the organic light emitting layer 102 side, that is, ni> In the case of ns, as shown in P1 and P2 of FIG. 9, total reflection may occur with respect to incident light. That is, in FIG. 9, a state in which light that is about to enter the substrate 104 from the transparent electrode 103 is totally reflected (P1), and a state in which light that is about to enter the air layer 105 is totally reflected (P2). )It is shown. The occurrence of such total reflection depends on the angle of incident light, and the critical angle θc, which is the angle at which total reflection occurs, can be expressed by the following equation (2). Light incident at an angle greater than the critical angle θc undergoes total reflection, and 100% reflection occurs when the absorption of the material is ignored. For this reason, light cannot be extracted outside the device, resulting in a large loss.

  In such an organic EL element formed by laminating materials having different refractive indexes, loss of light extraction efficiency to the outside (a ratio indicating how much light emitted inside the element can be emitted) occurs. There is a problem. As a specific example, when a glass flat plate having a refractive index of 1.5 is used for the substrate 104, the light extraction efficiency extracted outside is generally said to be 20% or less. For this reason, various methods for improving the light extraction efficiency to the outside of the element have been proposed. For example, Patent Document 1 discloses a technique for improving the light extraction efficiency to the outside of the element by providing a microlens on the element substrate. Has been.

Japanese Patent No. 2773720

  However, in the configuration according to Patent Document 1, in order to effectively suppress total reflection occurring at the interface with air, it is necessary that the microlens has a sufficiently large lens diameter with respect to the light emitting area. When it is difficult to provide a microlens having a sufficiently large diameter with respect to the light emitting area, a sufficient total reflection suppressing effect cannot be obtained. To give a typical example, in an element application aiming at realization of a high-definition pixel size such as a display application, it is required to increase the density of the element layout, and the size is desired to be small. In view of physical interference between the microlenses and the increase in pixel density, it may be difficult to provide a sufficiently large microlens for the pixel area, and a sufficient total reflection suppression effect is obtained. There was a case that could not be done.

  Moreover, in the structure which concerns on patent document 1, since a microlens becomes convex shape, it will be easy to be damaged to this convex part, and it will become easy to get dirt, and it is hard to say that durability and antifouling property are favorable. Furthermore, when a plurality of microlenses are arranged, a concave-convex structure is formed, which makes it difficult to attach other optical members to the microlenses.

  The present invention has been made in view of the actual situation, and is relatively thin and does not bulky a planar light emitting element such as an organic EL, and is totally reflected at the interface between the substrate and the air layer, which is the outermost surface of the element that becomes a loss. The purpose is to provide an optical member or the like that can improve the light extraction efficiency of light extracted to the outside by reducing the amount of light emitted, and can also improve durability, antifouling property, and attachment of other members And

As a means for solving the above problems, the invention according to claim 1, an optical member to improve the light extraction efficiency by disposing the light extraction surface side of the planar light-emitting element, the light so with respect to the normal of the light extraction surface when arranged on the extraction side and obliquely, comprising a multilayer film optical member in which the product layer materials of different refractive index, the multilayer film optical member, the refractive index A plurality of regions having different lamination directions in which different materials are laminated and at least one of lamination intervals in which materials having different refractive indexes are repeatedly laminated are spatially divided as viewed from the light extraction surface. And
According to the first aspect of the present invention, the multilayer optical member is formed by laminating materials having different refractive indexes obliquely with respect to the normal line of the light extraction surface, and is incident at an angle close to the laminating direction. The light can be reflected in substantially the opposite direction and re-enter the planar light-emitting element, and the re-incident light can be reflected and scattered by the planar light-emitting element and partly outside the optical member. The angle can be converted into an angle that can be taken out. Note that the “stacking direction” refers to the normal direction of the surface in contact with materials having different refractive indexes, in other words, the direction in which the interval between repeated layers of materials having different refractive indexes is minimized.
For light incident at an angle opposite to the stacking direction (an angle close to a substantially right angle), first, the light travels straight inside the multilayer optical member, and the interface with the air layer outside the multilayer optical member. And the light reflected here becomes an angle close to the stacking direction, so that the multilayer optical member can reflect the light in the substantially opposite direction. It can be reflected again at the interface with the air layer outside the multilayer optical member and returned to the planar light emitting element side. Thereby, it is reflected and scattered in the planar light emitting element, and can be converted into an angle at which a part can be taken out of the optical member.
As a result, the light incident at any of the above angles can be converted in the reverse direction by the multilayer optical member. Therefore, the light that cannot be extracted to the outside in the absence of the multilayer optical member compared to the case without the multilayer optical member. That is, it is possible to increase the number of reflections between the air layer of light incident at an angle greater than the critical angle and the interface of the multilayer optical member, and the number of repetitions of reflection and scattering on the planar light emitting element. Thus, the light extraction efficiency can be improved.
In addition, since the materials having different refractive indexes are laminated obliquely with respect to the normal line of the light extraction surface, it is possible to give wavelength selectivity to the reflectance of light incident from the planar light emitting element side. .
In other words, by adjusting the thickness of materials with different refractive indexes, it is possible to easily set the optimal optical path length for reflecting light of a specific wavelength, so that it can act only on light of a wavelength close to the specific wavelength. As a result, the color purity of the specific color can be increased.
Furthermore, since materials with different refractive indexes are laminated obliquely with respect to the normal of the light extraction surface, light is emitted in a shape that does not use an uneven structure such as a microlens or prism (typically a film). Since it is possible to configure an optical member that improves the extraction efficiency, it can be made relatively thin so that the surface light emitting element is not bulky, and it is combined with other optical members with improved durability and antifouling properties. It becomes easy, and the attachment property with other members can also be improved.

According to a second aspect of the present invention, in the optical member according to the first aspect, the multilayer optical member has a plurality of unit regions formed by a combination of the plurality of regions, whereby the light extraction surface is arranged. It is characterized by the fact that it is divided into spaces.
According to a third aspect of the present invention, in the optical member according to the second aspect, the unit region includes a combination of three regions in which at least one of the stacking direction and the stacking interval is different.
According to a fourth aspect of the present invention, in the optical member according to any one of the first to third aspects, a diffusing optical member that diffuses incident light is provided .
According to the fourth aspect of the present invention, by combining the multilayer optical member with the diffusion optical member, it is possible to increase the effect of reflection and diffusion on the light reflected by the multilayer optical member, so that more light is emitted. It becomes possible to convert to an angle that can be taken out. The arrangement of the diffusing optical member with respect to the multilayer optical member may be on either the light extraction surface side or the planar light emitting element side.

The invention of claim 5 is an optical member according to claim 1, wherein the multilayer film the light extraction surface side of the material or the refractive index n _out of the space of the optical _member, the planar If the refractive index of the light emitting element side of the material was n _in, the multilayer film angle in the stacking direction of the optical member, with respect to the normal direction of the light extraction surface, the critical angle θc as determined by n _out, n _in = Arcsin (n _out / n _in ) or more.
According to the invention described in claim 5, when the refractive index of the material or space on the light extraction surface side is n _out and the refractive index of the material on the planar light emitting element side is n _in , the multilayer optical member is laminated. By setting the angle of the direction to a critical angle θc = arcsin (n _out / n _in ) or more determined from n _out and n _in , light having a critical angle or more that cannot be used without the optical member according to the present invention. More light can be reflected, and the light extraction efficiency can be further improved.
In addition, for the light incident in the front direction that can be taken out even in the absence of the optical member according to the present invention, that is, in the direction along the normal of the light extraction side surface of the planar light emitting element, the lamination direction of the multilayer optical member Therefore, the reflection effect by the multilayer optical member does not work, and the phenomenon that this light returns to the planar light emitting element side can be suppressed.

The invention of claim 6 is an optical member according to claim 1, wherein the multilayer film optical member, the different materials of said refractive index with respect to the normal of the light extraction City surface has a plurality of laminated structures laminated obliquely, the laminated structure is characterized in that at least one is different from the laminating direction and the laminated interval.
According to the invention described in claim 6, since there are a plurality of laminated structures in the multilayer optical member, it is possible to set a plurality of optimum wavelengths, incident light, and optimum angles of reflected light, and a set of optimum wavelengths, incident light. Optimum wavelength, incident light, and optimum angle of reflected light can be set for light with a wavelength or angle other than the optimum angle of light and reflected light. Therefore, the luminance can be further improved. The optimum wavelength means the wavelength of light in which the reflection effect by the laminated structure set at a predetermined lamination interval in the optical member is strong, and the optimum angle of incident light and reflected light is reflected substantially in the reverse direction by the laminated structure. The angle of light that can be caused.

The invention according to claim 7, the planar light-emitting element, and an optical member according to any one of claims 1 to 6 disposed on the light extraction surface side of said surface-shaped light-emitting element, in that it comprises This is an EL display device.
According to the seventh aspect of the present invention, the light extraction efficiency can be improved, and a brightness improvement effect can be obtained.

According to an eighth aspect of the present invention, in the EL display device according to the seventh aspect, the planar light emitting element has a plurality of display pixels, and the optical member is the plurality of regions of the multilayer optical member. Are arranged so as to have the same combination for each of the display pixels .
According to a ninth aspect of the present invention, in the EL display device according to the eighth aspect, the display pixel includes a red region that emits red light, a green region that emits green light, and a blue region that emits blue light. And the plurality of regions of the multilayer optical member are different in at least one of the stacking direction and the stacking interval corresponding to the red region, the green region, and the blue region. It is characterized by comprising the following areas.
According to the invention described in claim 9, since many of the image display devices display an image by a combination of pixels of different colors such as red, green, and blue for each pixel, a multilayer optical system is provided for each pixel. By setting the stacking direction of the members and the stacking interval, it is possible to improve the luminance and add a color correction effect due to the wavelength selectivity of the stacked structure.

According to the present invention, it is possible to improve the light extraction efficiency of light extracted to the outside, and to improve durability, antifouling property, and attachment of other members.

It is a figure which shows the structure of the organic EL element which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the organic EL element which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the optical member which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the organic EL element which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the optical member which concerns on the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the organic electroluminescence display which concerns on the 4th Embodiment of this invention. It is a figure explaining the Example of this invention. It is a figure explaining the Example of this invention. It is a figure which shows the structure of the conventional organic EL element.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
1 and 2 are views (XZ plane; incident plane) showing the structure of the organic EL element 1 according to the first embodiment of the present invention. In the first embodiment, the same components as those described with reference to FIG.

  As shown in FIGS. 1 and 2, the organic EL element 1 includes a back electrode 101, an organic light emitting layer 102, a transparent electrode 103, and a glass substrate 104, which are stacked in this order on the light extraction surface side (see FIG. 1). The optical member 10 is arranged on the middle arrow H side) to improve the light extraction efficiency. In the figure, reference numeral 105 denotes an air layer.

  The organic EL element body 2 emits light in the organic light emitting layer 102 by applying a voltage between the back electrode 101 and the transparent electrode 103, and this light is emitted from the transparent electrode 103 side to the outside of the element, that is, the air layer 105 side. Light is emitted to a certain light extraction surface side. The organic light emitting layer 102 is configured as a fluorescent organic compound capable of spontaneously emitting light in a predetermined color when energized. However, a desired color can be obtained by, for example, a configuration that colors the emitted light by overlapping color filters. It may be configured to emit light.

  The transparent electrode 103 is formed of a transparent material so as to transmit light from the organic light emitting layer 102. Specifically, the transparent electrode 103 is formed by a dry process such as vapor deposition or sputtering of ITO, IZO or the like. Since the glass substrate 104 can be a plastic substrate and a flexible EL element can be manufactured, the glass substrate 104 is simply referred to as a substrate 104 below. Note that an actual organic EL element is configured by laminating various thin film layers such as an electron transport layer and a hole transport layer, but in the present embodiment, the description is omitted for the sake of illustration.

Referring to FIG. 3, the optical member 10 is formed of a resin material in sheet or film form, laminated obliquely with respect to a normal V of the light extraction City surface of materials having different refractive index organic EL element body 2 That is, it is configured as a multilayer film optical member (multilayer film optical member).

To be more specific, the optical member 10 has a high refractive index member 11 and the low refractive index member 12 as materials of different refractive index, the normal V of the light extraction City surface of the organic EL element body 2 The organic EL element main body is configured by repeatedly laminating (plural) a high refractive index member 11 and a low refractive index member 12 set to a predetermined film thickness in a laminating direction 13 indicated by an arrow inclined to the angle α. it is constituted as a sheet or film shape along the second light extraction City surface. In other words, the optical member 10, a surface with high refractive index member 11 and the low refractive index member 12 is in contact with inclined with respect to the normal V of the light extraction City surface of the organic EL element body 2, high-refractive-index member 11 and the lower The refractive index member 12 is repeatedly laminated.

  The refractive indexes of the high refractive index member 11 and the low refractive index member 12 are appropriately set according to the refractive indexes of the substrate 104 and the air layer 105, and the angle α in the stacking direction 13 is determined from the organic light emitting layer 102. It is appropriately set according to the angle of the light to be reflected among the emitted light. In FIG. 3, D <b> 1 indicates an interval (stacking interval) in which the high refractive index member 11 and the low refractive index member 12 are repeatedly stacked. The stacking interval, that is, the film thickness of each material is also determined from the organic light emitting layer 102. It can be appropriately set according to the wavelength of the emitted light. Note that the stacking direction 13 can be said to be the direction in which the interval between repeated stacking of materials having different refractive indexes is minimized.

The behavior of light from the organic light emitting layer 102 in the organic EL element 1 described above (the action on the light by the optical member 10) will be described with reference to FIGS. 10, constituted by laminating a high refractive index material 11 and low refractive index material 12, and diagonal laminated to the normal V of the high-refractive-index material 11 and low refractive index material 12 light extraction City surface By repeatedly laminating along the direction 13, the light L <b> 1 (see FIGS. 1 and 3) incident at an angle close to the laminating direction 13 is reflected in a substantially opposite direction to be organic EL element body. 2 (L1 ′ in the figure). As shown in FIG. 1, the light L <b> 1 is irradiated from the organic light emitting layer 102, is refracted by the transparent electrode 103 and the substrate 104 as appropriate, and then enters the optical member 10, and a part thereof is transmitted through the optical member 10. To do.

  In addition, for the light L2 (see FIGS. 2 and 3) incident at an opposite angle (an angle close to a substantially right angle) with respect to the stacking direction 13, first, the optical member 10 is linearly moved, The light can be reflected at the interface with the air layer 105 and travel straight again in the optical member 10, and the light reflected here has an angle close to the stacking direction as referred to by an arrow in the figure. Therefore, the optical member 10 can reflect the light in substantially the opposite direction, and the light can be reflected again at the interface with the air layer 105 outside the optical member 10 and returned to the organic EL element body 2. (L2 ′ in the figure). The light L2 is irradiated from the organic light emitting layer 102 as shown in FIG. 2, is refracted by the transparent electrode 103 and the substrate 104, and then enters the optical member 10.

  For this reason, in this embodiment, since the light incident at any of the above angles can be converted in the reverse direction by the optical member 10, this incident light is reflected and scattered by the organic EL element body 2 (S1, S2 in the figure). It is possible to convert a part of the optical member 10 into an angle that can be extracted to the outside of the optical member 10, and light that cannot be extracted outside in the absence of the optical member 10 compared to the case without the optical member 10. That is, the number of reflections of the incident light between the air layer 105 and the optical member 10 at an angle greater than the critical angle (determined by the refractive index of the substrate 104 and the air layer 105 in this embodiment), and In addition, it is possible to increase the number of times that reflection and scattering within the organic EL element body 2 are repeated, and it is possible to improve the light extraction efficiency.

Further, in the present embodiment, by a structure in which materials having different refractive indices are laminated obliquely with respect to the normal of the light output shi surface, the wavelength-selective reflectance of light incident from the organic EL element main body 2 In other words, by adjusting the thickness of materials with different refractive indexes, it is possible to easily set the optimal optical path length for reflecting light of a specific wavelength, so that the wavelength is close to the specific wavelength. It can be made to act only on the light, and almost no effect on the light in the direction greatly different from the wavelength or the stacking direction. As a result, the color purity of the specific color can be increased. Furthermore, since the optical member 10 is a sheet or film shape that does not use a concavo-convex structure such as a microlens or a prism, and is a relatively thin structure that does not bulk the planar light emitting element, it has improved durability and antifouling properties. The combination with other optical members is facilitated, and the attachment of other members can be improved.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram (XZ plane; incident surface) showing the structure of the organic EL element 20 according to the present embodiment. Constituent elements similar to those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 4, the organic EL element 20 is diffused in the organic EL element body 2 (in the arrow H side in the figure) formed by sequentially laminating the back electrode 101, the organic light emitting layer 102, the transparent electrode 103, and the substrate 104. An optical member 23 formed by combining the optical member 21 and the multilayer optical member 22 is disposed.

  The diffusion optical member 21 disposed on the light extraction surface side of the substrate 104 is formed in a sheet or film shape, and is configured by dispersing light diffusion particles in a transparent resin, for example. A general thermoplastic resin, a thermosetting resin, or the like can be used as the transparent resin, and a transparent particle made of an inorganic oxide or a resin can be used as the light diffusion particle. In the present embodiment, the diffusing optical member 21 is configured by dispersing light diffusing particles in a transparent resin, but other modes may be used.

Multilayer optical member 22 is a similar to the optical member 10 described in the first embodiment, the organic EL element angle with respect to the normal V of the light extraction City surface of the main body 2 alpha tilted stacking direction 13 (the 1 reference embodiment), repeated a high refractive index member 11 and the low refractive index member 12 that is set to a predetermined thickness (s) is constituted by laminating, and light extraction City organic EL element body 2 It is configured as a sheet or film along the surface. In other words, in the present embodiment, the optical member 23 includes the diffusing optical member 21 and the multilayer optical member 22.

  The behavior of light from the organic light emitting layer 102 in the organic EL element 20 is the same as that described in the first embodiment, and the diffusion optical member 21 will be described with reference to FIGS. Light that is transmitted and incident at an angle close to the stacking direction 13 can be reflected in a substantially opposite direction and incident again on the organic EL element body 2. Further, light that has passed through the diffusing optical member 21 and is incident at an angle opposite to the stacking direction 13 (an angle close to a substantially right angle) is also reflected at the interface with the air layer 105 outside the optical member 23, It becomes possible to return to the organic EL element body 2.

  In this embodiment, since the optical member 23 is configured by combining the diffusing optical member 21 with the multilayer optical member 22, the action of reflection and diffusion with respect to the light reflected by the multilayer optical member 21 is increased. (See S3 in FIG. 4), and therefore, it is possible to convert to an angle at which more light can be extracted. The arrangement of the diffusing optical member 21 with respect to the multilayer optical member 22 may be on either the light extraction surface side or the organic EL element body 2 side.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. FIG. 5A shows the optical member 30 according to this embodiment. The optical member 30 is different in structure from the optical members 10 and 23 described in the first and second embodiments, but the arrangement position and the like with respect to the organic EL element are the same as those in the first and second embodiments. This is the same as the embodiment.

The optical member 30 as shown in FIG. 5 (A), the normal consists by several superimposed layered structure of laminating oblique to the light extraction City surface materials having different refractive index (in other words, a plurality Yes) ones a is one in which the laminated intervals different materials stacked direction and refraction index different materials refraction index are laminated are repeatedly laminated is configured to have a plurality of different layered structures.

That is, with reference to FIG. 5A, the optical member 30 is configured to extract the high refractive index member 31 and the low refractive index member 32 having a predetermined stacking distance D2 (film thickness) from the light extraction of the organic EL element. A high-refractive index member 35 and a low-refractive index member 36 each having a predetermined stacking interval D3 (film thickness) are set in a stacked structure 34 that is repeatedly stacked in a stacking direction 33 that is inclined at an angle β with respect to the normal V of the cut surface. and it is configured by superimposing a laminate structure 38 which repeatedly stacked in the stacking direction 37 inclined an angle η with respect to the normal V of the light extraction City surface of the organic EL element. That is, the optical member 30 includes a plurality of stacked structures 34 and stacked structures 38 that are two types of stacked patterns. The angle η is set to be larger than the angle β, and the stacking interval D2 is set longer than the stacking interval D3. The high refractive index member 31 and the high refractive index member 35 are made of the same material, and the low refractive index member 32 and the low refractive index member 36 are also made of the same material.

  When the optical member 30 according to the third embodiment is used, it is possible to set a plurality of optimum wavelengths, incident light and optimum angles of reflected light, and a set of optimum wavelengths, incident light and reflected light. It is possible to set the optimum wavelength, the incident light, and the optimum angle of the reflected light for light with a wavelength or angle other than the optimum angle, and it is possible to give a reflection effect to the light at a plurality of specific wavelengths. Since the amount of light that can be used increases, the luminance can be further improved. The optimum wavelength refers to the wavelength of light in which the reflection effect by the laminated structure set at a predetermined lamination interval in the optical member 30 is strong, and the optimum angle of incident light and reflected light is substantially opposite depending on the laminated structure. The angle of light that can be reflected.

  5A illustrates a configuration in which the stacked structure 34 and the stacked structure 38 that are inclined in the same direction with respect to the normal line V of the light extraction surface overlap each other. However, as illustrated in FIG. 5B, the light extraction surface is illustrated. A configuration in which stacked structures inclined in different direction sides (reverse direction sides) with respect to the normal line V may be superposed. That is, in the optical member 30 ′ shown in FIG. 5B, one stacking structure is set in a stacking direction facing the angle δ, and the other stacking structure is inclined to the opposite side across the angle δ and the normal V. The stacking direction is set. Note that such a configuration does not have to be the same incident surface. In the present embodiment, both the stacking direction and the stacking interval are different between the stacked structure 34 and the stacked structure 38. Any of the stacking intervals may be varied, and the number of overlapping may be three or more.

<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. FIG. 6 is a longitudinal sectional view (XY sectional view, Z is a light extraction side surface) of the EL display device 40 according to the present embodiment.

  The EL display device 40 shown in FIG. 6 is divided into a red region 41, a green region 42, and a blue region 43 for each pixel (the red region 41, the green region 42, and the blue region 43 are combined to form a single pixel). . As the EL element in the EL display device 40, for example, the organic EL element 44 having the same configuration as that of the organic EL element 20 described in the second embodiment is used. The peak of the emission wavelength of each pixel is set to 650 nm in the red region 41, 550 nm in the green region 42, and 450 nm in the blue region 43.

  The organic EL element 44 includes an optical member 45 similar to the configuration described in the second embodiment, and this optical member 45 has at least a stacking direction and a stacking interval so as to correspond to the position and color of each pixel. The area is divided into regions (45R, 45G, 45B) in which one is changed.

  In the EL display device 40 according to this embodiment, the optical member 45 has an optimum configuration for each pixel by setting the stacking direction and stacking interval of the optical members 45 for each pixel. Thus, it is possible to add a color correction effect due to the improvement in luminance and the wavelength selectivity of the laminated structure.

  Next, examples of the present invention will be described below. In this example, the refractive index and the like are specifically set for each component of the organic EL display device 20 according to the second embodiment.

  Referring to FIGS. 7 and 8, the organic light emitting layer 102 is configured as a green organic light emitting layer capable of emitting green light that emits light in the vicinity of a wavelength of 530 nm, and its refractive index is “1.7”. The transparent electrode 103 has a refractive index of “2.0”, and the glass substrate 104 has a refractive index of “1.5”. In this case, the critical angle θc between the substrate 104 and the air layer (refractive index 1.0) is 41.8 degrees.

Refractive index _{n a} of the high refractive index material 11 in the optical member 23 is set to _"n a = 1.6", the refractive index _{n b} of the low refractive index material 12 is set to _"n a = 1.5", respectively membrane The layers were stacked with thicknesses d _a = 166 nm and d _b = 177 nm, and the optical path length was n × d = 532/2. The stacking direction was 50 degrees with respect to the surface normal.

  When the behavior of light in this example was observed, with reference to FIGS. 7 and 8, the light L3 emitted from the organic light emitting layer 102 near the front surface (0 degree) of the substrate 104 remains as it is, and some refraction occurs at each interface. It reaches the diffusing optical member 21, and after passing through the diffusing optical member 21, it reaches the multilayer optical member 22. However, since it is incident at a significantly different angle from 50 degrees in the stacking direction of the multilayer optical member 22, reflection occurs. It was confirmed that it was possible to inject into the air layer.

  When the behavior of the light L4 emitted at 40 degrees in the organic light emitting layer 102 was observed, first, refraction occurs at the interface between the organic light emitting layer 102 and the transparent electrode 103, and proceeds in the direction of 33.1 degrees within the transparent electrode 103. . Next, it bends to 46.8 degrees due to refraction at the interface between the transparent electrode 103 and the substrate 104, passes through the diffusion optical member 21 at an incident angle of 46.8 degrees, and enters the multilayer optical member 22. Since the light is incident at an angle close to the optimum illumination light angle of 50 degrees, the light is reflected at substantially the same angle, and the light beam travels in the opposite optical path to reach the diffusion optical member 21 (L4 '). Here, the light is diffused, and a part of the light is converted into an angle that can be taken out to the air layer 105, so that the improvement of the taking-out efficiency was confirmed. In addition, it was confirmed that a part of the organic light emitting layer 102 passed through the organic light emitting layer 102, reflected by the back electrode 101, returned to the multilayer film optical member 10 again, and the same process was repeated with some of the critical angles remaining.

  When the behavior of the light 33 of 62 degrees or more is observed in the organic light emitting layer, refraction occurs at the interface between the organic light emitting layer 102 and the transparent electrode 103, and becomes 48.6 degrees or more in the transparent electrode. For this reason, total reflection occurs at the interface between the transparent electrode 103 and the substrate 104, and the substrate cannot be taken out, resulting in a loss. In addition, as described above, light that has passed through the diffusion optical member 21 and is incident at a reverse angle (an angle close to a substantially right angle) with respect to the stacking direction 13 is reflected at the interface with the air layer 105, and the organic EL It is possible to return to the element body 2.

As described above, when the stacking direction of the optical member 23 is set to 50 degrees, which is 41.8 degrees or more, which is the critical angle θc with respect to the surface normal, light in the vicinity of 40 to 50 degrees is effectively used in the organic light emitting layer 102. It was confirmed that the light extraction efficiency was improved and the light extraction efficiency was improved. That is, the stacking direction of the stacked structure in the multilayer optical member 22 is set to n _out (in this example, “1.0” of the air layer 105), the refractive index of the material or space on the light extraction surface side, and the surface light emitting element side. When the refractive index of the material is n _in (in this example, “1.5” of the substrate 104), if the critical angle θc = arcsin (n _out / n _in ) determined from n _out and n _in is greater than or equal to It was confirmed that more light with a critical angle or more can be reflected, and the light extraction efficiency can be further improved.

  Although the embodiment and examples of the present invention have been described above, the configuration in the above embodiment is an example of the present invention, and it goes without saying that various modifications can be made without departing from the gist of the present invention. Nor. For example, in the above-described embodiment, an example in which the optical member according to the present invention is used for an organic EL element has been described. However, the present invention can also be suitably used in an inorganic EL or FED.

1, 20, 44 Organic EL element 10, 23, 30, 45 Optical member 21 Diffusing optical member 22 Multilayer optical member 31, 35 High refractive material 32, 36 Low refractive material 34, 38 Laminated structure 40 EL display device 101 Rear electrode 102 Organic light emitting layer 103 Transparent electrode 104 Glass substrate 105 Air layer

Claims (9)

An optical member for improving the light extraction efficiency by being arranged on the light extraction surface side of the planar light emitting element,
So that oblique with respect to a normal of the light extraction surface when arranged on the light extraction surface side, comprising a multilayer film optical member in which the product layer materials of different refractive index,
The multilayer optical member is:
Space-divided into a plurality of regions in which at least one of a stacking direction in which the materials having different refractive indexes are stacked and a stacking interval in which the materials having different refractive indexes are repeatedly stacked is different as viewed from the light extraction surface. an optical member, characterized in that <br/> you are. The multilayer optical member is:
A plurality of unit regions formed by a combination of the plurality of regions are arranged to be spatially divided as viewed from the light extraction surface.
The optical member according to claim 1. The unit region includes a combination of three regions in which at least one of the stacking direction and the stacking interval is different.
The optical member according to claim 2. The optical member according to any one of claims 1 to 3, characterized in <br/> further comprising a diffusing optical element for diffusing light incident Isa. Wherein the light extraction surface side of the material or space refractive index n _out of the multilayer film optical _member, if the refractive index of the planar light-emitting element side of the material was n _in,
An angle in the stacking direction of the multilayer optical member is not less than a critical angle θc = arcsin (n _out / n _in ) determined by n _out and n _in with respect to a normal direction of the light extraction surface. The optical member according to any one of claims 1 to 4 . The multilayer optical member is:
It has a plurality of laminated structure of laminating different materials the refractive index at an angle relative to the normal of the light extraction City surfaces, each laminated structure, the feature that at least one is different from the laminating direction and the laminated interval The optical member according to any one of claims 1 to 5 . A planar light emitting device;
The optical member according to any one of claims 1 to 6 , disposed on a light extraction surface side of the planar light emitting element ,
EL display device comprising <br/> comprise a. The planar light emitting element is
Having a plurality of display pixels,
The optical member is
The EL display device according to claim 7, wherein the plurality of regions of the multilayer optical member are arranged in the same combination for each display pixel . The display pixel is
A red region that emits red light, a green region that emits green light, and a blue region that emits blue light,
The plurality of regions of the multilayer optical member are:
Corresponding to the red region, the green region, and the blue region, it is composed of three types of regions in which at least one of the stacking direction and the stacking interval is different.
The EL display device according to claim 8.

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